title: Reduction of exercise capacity in children from summer to winter is associated with lower sporting activity: a serial study.
abstract: BACKGROUND
  Declining activity in children over the past decades is thought to be one of the main risk factors for an early development of exercise intolerance and obesity. Taking this background into account, this prospective study investigated the seasonal change of children's physical activity and its association with objective measures of exercise capacity.
  
  
  METHODS
  A total of 96 children from two schools in Munich (42 girls, age 12.4 ± 0.8 y) underwent a cardiopulmonary exercise test (CPET) and an assessment of their daily activities (school sport, club sport, leisure sport) twice. Baseline testing was conducted in summer 2011. Follow-up examination was performed during winter 2012.
  
  
  RESULTS
  From summer to winter, self-reported sporting activity decreased from 10.6 ± 4.1 to 8.5 ± 4.3 h/wk (P < 0.001) as school sport (P < 0.001) and leisure sport activities (P = 0.002) decreased, but the activity associated with club sport did not (P = 0.700). In parallel, peak oxygen uptake (VO2) declined from 102.0 ± 17.5 to 96.9 ± 17.9 % of predicted (P < 0.001). This decline in VO2 was associated with a reduction in overall sporting activity (r = 0.234; P < 0.032).
  
  
  CONCLUSIONS
  Enhancing sporting activity in children during winter might be important to maintaining their exercise capacity.
authors.affiliation: Institute of Preventive Pediatrics, Technische Universität München, München, Germany.
authors.forename: Jan
authors.initials: J
authors.lastname: Müller
authors.forename: Birgit
authors.initials: B
authors.lastname: Böhm
authors.forename: Julia
authors.initials: J
authors.lastname: Elmenhorst
authors.forename: Christiane
authors.initials: C
authors.lastname: Barta
authors.forename: Renate
authors.initials: R
authors.lastname: Oberhoffer
mesh_terms: D000203:Activities of Daily Living; D000293:Adolescent; D000886:Anthropometry; D002648:Child; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005260:Female; D005858:Germany; D006801:Humans; D008297:Male; D010101:Oxygen Consumption / Q000502:physiology; D012621:Seasons; D057566:Self Report